MBX insider purchase: 20,000 shares at $13.60–$13.6399 range

Rhea-AI Filing Summary

MBX Biosciences (MBX) reported an insider share purchase by its President & CEO and Director on 10/20/2025. The reporting person bought 20,000 shares of common stock at a weighted average price of $13.6395, with trades executed between $13.60 and $13.6399.

Following the transaction, the filing lists 481,397 shares as directly owned and 468,277 shares as indirectly owned by a trust. The trust is identified as the P. Kent Hawryluk Revocable Trust, with the reporting person serving as trustee.

Insights

Securities law analyst

Routine Form 4 showing a CEO open-market purchase at $13.6395.

The filing records an open-market acquisition of 20,000 shares on 10/20/2025 at a weighted average $13.6395, with individual trades ranging from $13.60 to $13.6399. Such weighted-average disclosures are typical, and the filer offers to provide full breakdowns upon request.

Post-transaction holdings are split between direct ownership of 481,397 shares and indirect ownership of 468,277 shares via a trust, consistent with Section 16 reporting of beneficial ownership categories.

As a routine ownership update by the President & CEO and Director, this is administratively informative; actual impact depends on broader context not included here.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Hawryluk P. Kent

(Last) (First) (Middle)

C/O MBX BIOSCIENCES, INC.

11711 N. MERIDIAN STREET, SUITE 300

(Street)

CARMEL IN 46032

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
MBX Biosciences, Inc. [ MBX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	President & CEO

3. Date of Earliest Transaction (Month/Day/Year)
10/20/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock								481,397	D
Common Stock	10/20/2025		P		20,000	A	$13.6395(1)	468,277	I	By Trust(2)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $13.60 to $13.6399, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.

2. Shares held by the P. Kent Hawryluk Revocable Trust dated January 25, 2011, of which the Reporting Person serves as trustee. The Reporting Person disclaims beneficial ownership except to the extent of any pecuniary interest therein, and this report shall not be deemed an admission that such shares are beneficially owned by him for Section 16 or any other purpose.

	/s/ Richard Bartram, attorney-in-fact	10/21/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What did MBX (MBX) disclose in this Form 4?

An insider purchase of 20,000 shares of common stock on 10/20/2025.

What was the purchase price in MBX’s Form 4?

A weighted average price of $13.6395, with trades from $13.60 to $13.6399.

Who is the reporting person in the MBX Form 4?

The company’s President & CEO and Director.

How many MBX shares does the insider hold after the transaction?

481,397 shares directly and 468,277 shares indirectly via a trust.

What entity holds the indirect MBX shares?

The P. Kent Hawryluk Revocable Trust, with the reporting person as trustee.